1. Field of the Invention
The present invention relates to an optical element such as a lens element suitably applicable to optical communication devices, tools and systems. Also, the invention relates to a method for manufacturing the optical element.
2. Prior Art
The surface mount technology (SMT) has been widely known as one of mass production technologies for producing optical modules for use in the optical communication at a low cost. According to this technology, for instance, the outward form of parts such as laser diodes, lens elements and so forth necessary for constituting the optical module are made in advance with high precision, and these mount parts are arranged on a V-shaped groove formed on the surface of a silicon substrate, with high precision of a sub-micron order. Furthermore, in some case, the parts to be mounted are given, in advance, an alignment mark for positioning thereof, taken by a CCD camera, and then arranged by means of the image recognition technology. In case of using these technologies, however, as the parts are arranged without monitoring the quantity of light incident on the optical fiber, the manufacturing precision and the positioning precision give a certain influence to the quantity of light finally incident on the optical fiber. Therefore, it is very needed to manufacture and align each part with high precision.
The lens element usable in SMT has a comparatively large external dimension, for instance, 1 mm or so in terms of the outward diameter. Also, in case of those which are formed by the embossing process, the necessary precision can be hardly obtained, thus undesirable problems to the surface mount being caused.
Recently, there has been devised a micro-lens manufactured by using the photolithographic etching process. In case of lens of this kind, however, as there is a certain limitation with regard to the dimension in the direction of the optical axis of the lens, the lens size can not help becoming small, thus the handling of it becoming more difficult.
The invention has been made in view of the problems as described above, and an object of the invention is to provide an optical element which can be handled with ease and mounted on a supporting means for supporting it with high precision and efficiency, and also to provide a method for manufacturing such an optical element as described above.
In order to solve the problems as mentioned above, according to the first aspect of the invention, there is provided a method for manufacturing an optical element which is mounted on a supporting substrate having a groove for use in mounting the optical element thereon. This method includes the manufacturing steps as will be described in the following. First of all, at least one light beam conversion portion is formed on one surface of an optical substrate. In the next, the first groove portion is provided by removing a predetermined region on one side of the periphery of the light beam conversion portion up to a predetermined depth from the surface of the predetermined region. With this, there are formed an edge portion along a part of the periphery of the light beam conversion portion, an end face made up of the edge portion and a part of the light beam conversion portion surrounded by the above edge portion, and the first side wall which has the periphery of the end face as the one end thereof and is made up of a part of the side wall of the first groove portion, and is formed such that it comes into contact with the mounting groove of the supporting substrate. Furthermore, the second groove portion is formed by removing a predetermined region on the other side of the optical substrate up to a predetermined depth from the surface of the above predetermined region. With this, there are formed an end face made up of a part of the surface of the optical substrate, and the second side wall which has the periphery of the end face as the one end thereof and is made up of a part of the side wall of the second groove portion, and is formed such that it comes into contact with the mounting groove of the supporting substrate. Still further, the optical substrate is cut along a predetermined cutting line, thereby obtaining an optical element which is provided with at least one light beam conversion portion and the first side wall corresponding to the light beam conversion portion, at least one second side wall, a side face formed of a part of the bottom face of the first groove portion, a side face formed of a part of the bottom face of the second groove portion, and the side face formed of a part of the surface of the optical substrate.
Here, the light beam conversion portion means those which have the function of converting the light beam, for instance, the function of converging, diverging, reflecting, deflecting the light beam. Also, depending on the arrangement condition of it, the light beam conversion portion includes those which convert the incident light beam into parallel light rays, or split the incident light beam into a plurality of light beams. The lens, diffractive optical element, and so forth are concrete examples of the light beam conversion portion.
The optical substrate may be formed by means of a crystalline substrate such as a silicon crystal substrate. The crystalline substrate may be formed by using materials other than silicon, for instance, GaAs, InP, GaP, SiC, Ge and so forth.
According to the constitution as described above, it is possible to manufacture an optical element which is able to have an arbitrary thickness in the direction vertical to the surface of the light beam conversion portion. Furthermore, as above-mentioned manufacturing method includes the step of forming the side wall having a shape capable of coming into contact with the groove for mounting use, it becomes possible to manufacture an optical element which can be mounted and arranged on its supporting means with ease, high precision, and high efficiency.
Furthermore, according to the second aspect of the invention, there is provided an optical element including a handling portion having the first side face and the second side face opposing to the first side face; a thin thickness portion extending from the handling portion, having the first stepped face with a step as formed to inwardly direct to the first side face and the second stepped face with a step as formed to inwardly directing to the second side face, each of the first and second stepped faces being constituted as side faces thereof; the first projection portion having the first end face extended from the first side face, the first side wall of which one end is located on the first end face while the other end thereof is located on the first stepped face, and projecting in a boundary face between the first side face and the first stepped face; the second projection portion having the second end face extended from the second side face, the second side wall of which one end is located on the second end face while the other end thereof is located on the second stepped face, and projecting in a boundary face between the second side face and the second stepped face; and a light beam conversion portion is formed in a predetermined part of a region spreading over the first end face and the first side face portion in the vicinity thereof.
According to such a constitution of the optical element as described above, as the optical element is provided with a handling portion, the handling of the optical element is very much facilitated in the mounting process of it.